Emerson SI-PROFIBUS

66 Unidrive M SI-PROFIBUS User Guide
Issue Number: 3
12.3 Main Setpoint
Main Setpoint is the speed reference defined in the PROFIdrive profile.
It is scaled such that -32768 to +32767 is -200% to +200% of the maximum speed
clamp (Pr 01.006). The converted value is then written to drive digital speed reference 1
(Pr 01.021).
The formula used for this conversion is:
Example 1 - Open loop drive
The drive maximum speed clamp (Pr 1.06) = 50.0 Hz
The main setpoint value sent from the master to the drive is 13107
Giving:
Example 2 - Closed loop / servo drive
The drive maximum speed clamp (Pr 1.06) = 1500.0 rpm
The main setpoint sent from the master to the drive is 10923
Giving:
12.4 Main Actual Value
Main Actual Value is the speed feedback reference defined in the PROFIdrive profile.
It is scaled such that -32768 to +32767 is ±200 % of the maximum speed clamp (Pr
01.006). The converted value is derived from:
•Pr 02.001 for open loop drive operation.
•Pr 03.002 RFC-A or RFC-S drive operating modes.
The formula used for this conversion is:
Where SF is the speed feedback parameter, i.e. Pr 02.001 or Pr 03.002 depending upon
the drive operating mode.
Example 1 - Open loop drive
The drive maximum speed clamp (Pr 01.006) = 50.0 Hz
The drive post ramp reference (Pr 02.001) = 35.0 Hz
Pr 01.021
Main Setpoint Max Speed Clamp×
16384
------------------------------------------------------------------------------------------------ -=
Pr 01.021
13107 50.0×
16384
------------------------------------ 40.0Hz==
Pr 01.021
10923 1500.0×
16384
------------------------------------------ - 1000.0rpm==
Main Actual Value
SF 16384×
Max Speed Clamp
---------------------------------------------------=